Culture-negative surgical site infections.

BACKGROUND: The appearance of postoperative surgical site infection (SSI) in the absence of culturable bacterial pathogens is a common dilemma for the surgeon. METHODS: The literature was searched through references to primary articles, as well as a MEDLINE review, for reports of culture-negative SSIs. RESULTS: Potential causes of culture-negative SSIs include prior antimicrobial therapy; the presence of fastidious or slow-growing microorganisms such as mycobacteria, Mycoplasma spp., and Legionella spp.; infection caused by mundane bacteria that may be dismissed as "contaminants"; factitious infection; and others. CONCLUSIONS: We review the recognized causes of "culture negative" SSIs and discuss the laboratory capabilities that may enhance recognition of many of these pathogens and management options.

Outcomes of community-acquired, methicillin-resistant Staphylococcus aureus, soft tissue infections treated with antibiotics other than vancomycin.

Community-acquired, methicillin-resistant Staphylococcus aureus (cMRSA), soft tissue infections are becoming increasingly prevalent in the outpatient setting. Few studies have been specifically designed to examine the efficacy of oral antibiotic therapy for these infections. We performed an observational study to determine the effect of alternative, orally administered antibiotics on cMRSA soft tissue infections. Consecutive patients between January 2001 and March 2004 who had skin or soft tissue infections from which cMRSA was isolated and who had never received vancomycin were studied through retrospective and concurrent review. Primary outcome measures were improvement or resolution of infection 5 and 14 days after initiation of treatment with orally administered antibiotics and rates of recurrence within 30 days after completion of treatment. Thirty subjects met the inclusion criteria. Twenty-one subjects received either clindamycin, trimethoprim/sulfamethoxazole, doxycycline/minocycline, or a fluoroquinolone. Five subjects received a beta-lactam antibiotic with abscess drainage, and four subjects underwent abscess drainage alone. Improvement was noted for all subjects at 5 days, complete resolution of infection occurred for all subjects by 14 to 17 days, and in no case did relapse occur within 30 days. cMRSA skin and soft tissue infections can be successfully treated with orally administered antibiotics to which the organism has demonstrable in vitro susceptibility.

Bacteria recovered from patients admitted to a deployed U.S. military hospital in Baghdad, Iraq.

The predominant bacteria and antimicrobial susceptibilities were surveyed from a deployed, military, tertiary care facility in Baghdad, Iraq, serving U.S. troops, coalition forces, and Iraqis, from August 2003 through July 2004. We included cultures of blood, wounds, sputum, and urine, for a total of 908 cultures; 176 of these were obtained from U.S. troops. The bacteria most commonly isolated from U.S. troops were coagulase-negative staphylococci, accounting for 34% of isolates, Staphylococcus aureus (26%), and streptococcal species (11%). The 732 cultures obtained from the predominantly Iraqi population were Klebsiella pneumoniae (13%), Acinetobacter baumannii (11%), and Pseudomonas aeruginosa (10%); coagulase-negative staphylococci represented 21% of these isolates. These differences in prevalence were all statistically significant, when compared in chi2 analyses (p < 0.05). Antimicrobial susceptibility testing demonstrated broad resistance among the Gram-negative and Gram-positive bacteria.

Bacteriology of war wounds at the time of injury.

Bacterial contamination of war wounds occurs either at the time of injury or during the course of therapy. Characterization of the bacteria recovered at the time of initial trauma could influence the selection of empiric antimicrobial agents used to prevent infection. In the spring of 2004, U.S. military casualties who presented to the 31st Combat Support Hospital in Baghdad, Iraq, with acute traumatic injuries resulting in open wounds underwent aerobic culture of their wounds to identify the bacteria colonizing the wounds. Forty-nine casualties with 61 separate wounds were evaluated. Wounds were located predominantly in the upper and lower extremities and were primarily from improvised explosive devices or mortars. Thirty wounds (49%) had bacteria recovered on culture, with 40 bacteria identified. Eighteen casualties (20 wounds) had undergone field medical therapy (irrigation and/or antimicrobial treatment); six of these had nine bacterial isolates on culture. Of the 41 wounds from 31 patients who had received no previous therapy, 24 grew 31 bacteria. Gram-positive bacteria (93%), mostly skin-commensal bacteria, were the predominant organisms identified. Only three Gram-negative bacteria were detected, none of which were characterized as broadly resistant to antimicrobial agents. The only resistant bacteria recovered were two isolates of methicillin-resistant Staphylococcus aureus (MRSA). Our assessment of war wound bacterioly soon after injury reveals a predominance of Gram-positive organisms of low virulence and pathogenicity. The presence of MRSA in wounds likely reflects the increasing incidence of community-acquired MRSA bacteria. These data suggest that the use of broad-spectrum antibiotics with efficacy against more resistant, Gram-negative bacteria, such as Pseudomonas aeruginosa and Acinetobacter spp., is unnecessary in early wound management.

The remote diagnosis of malaria using telemedicine or e-mailed images.

We determined the ability of blinded remote expert microscopy to identify malaria parasites through transmission of malaria smear images via telemedicine and as e-mail attachments. Protocols for malaria smear transmission included: (1) transmission of sender-selected televised smears at various bandwidths (Bw), (2) transmission of remote reader-directed televised smears at various Bw, and (3) transmission of digital photomicrographs as e-mail attachments. Twenty (14%) of 147 sender-selected, and 13 (6%) of 221 reader-directed, images were deemed unreadable by slide readers. The presence or absence of malaria was correctly identified in 98% of the remaining images. Sixty-four (34%) of 190 digital microphotographs were deemed unreadable, while the presence or absence of malaria was correctly identified in 100% of the remaining images. Correct speciation ranged from 45% to 83% across various transmission methods and Bw. The use of telemedicine and e-mail technology shows promise for the remote diagnosis of malaria.

Effect of maximizing a travel medicine clinic's prevention strategies.

BACKGROUND: Even among travelers who undergo evaluation in travel medicine clinics, illnesses develop despite the emphasis placed on prevention. It is possible that travel-associated disease rates may be modified by maximizing access to care and augmenting educational methods of disease prevention. Use of alternative preventive measures such as alcohol hand gel sanitizers may also alter illnesses among travelers. METHODS: We assessed medical outcomes in a travel population cared for in the setting of free vaccinations, medications, and travel medicine consultation, in which personal preventive measures were presented in numerous formats by a physician specializing in infectious diseases. An initial demographic questionnaire was administered at the time of travel consultation. A post-travel telephone interview conducted 2 weeks after return from travel evaluated illness while abroad, illness upon return, and adherence to travel recommendations. An assessment was also performed regarding the utility of an alcohol hand gel sanitizer. RESULTS: One hundred fifty-five travelers were evaluated (primarily older, well-educated US-born travelers, on vacation with family or coworkers). Travelers filled their prescriptions 98% of the time; 77% reported adherence to antimalarial chemoprophylaxis. Sixty-four percent of travelers developed illness abroad, and 20% developed illness upon return. The most frequent complaints were diarrhea and upper respiratory illness. Ten percent of travelers altered their itinerary owing to illness. The use of alcohol hand gel sanitizers did not appear to impact the development of diarrhea or respiratory illnesses. CONCLUSION: In this small group of travelers, access to free consultation, vaccinations, and medications along with presentation of personal protective measures in various formats did not seem to influence the development of illnesses among travelers. Although not rigorously analyzed, alcohol hand gel sanitizers did not seem to alter diarrhea or respiratory tract illness rates. These data highlight the need for new or more effective methods to prevent illness among travelers.

Comparison of short-course (5 days) and standard (10 days) treatment for uncomplicated cellulitis.

BACKGROUND: Cellulitis is a condition routinely encountered in the primary care setting. No previous study has compared a short (5 days) vs standard (10 days) course of therapy of the same antibiotic in patients with uncomplicated cellulitis. METHODS: We performed a randomized, double-blind, placebo-controlled trial to determine if 5 days of therapy has equal efficacy to 10 days of therapy for patients with cellulitis. Of 121 enrolled subjects evaluated after 5 days of therapy for cellulitis, 43 were randomized to receive 5 more days of levofloxacin therapy (10 days total antibiotic treatment), and 44 subjects to receive 5 more days of placebo therapy (5 days of total antibiotic treatment). Levofloxacin was given at a dose of 500 mg/d. Subjects were not randomized if they had worsening cellulitis, a persistent nidus of infection, a lack of any clinical improvement, or abscess formation within the first 5 days of therapy. The main outcome measure was resolution of cellulitis at 14 days, with absence of relapse by 28 days, after study enrollment. RESULTS: Eighty-seven subjects were randomized and analyzed by intention to treat. There was no significant difference in clinical outcome between the 2 courses of therapy (success in 42 [98%] of 43 subjects receiving 10 days of antibiotic, and 43 [98%] of 44 subjects receiving 5 days of antibiotic) at both 14 and 28 days of therapy. CONCLUSION: In patients with uncomplicated cellulitis, 5 days of therapy with levofloxacin appears to be as effective as 10 days of therapy.

History of U.S. military contributions to the study of viral hepatitis.

Epidemic jaundice, although known by armies since ancient times, became a concern of the U.S. military only after outbreaks occurred during World War II. Early work by military investigators defined, for the first time, the existence of two different forms of hepatitis. Subsequently, investigators described the effective prevention of symptomatic hepatitis using immune serum globulin. Military researchers contributed to the isolation of and testing for the virus of infectious hepatitis, work that was then instrumental in the designing and fielding of a hepatitis A vaccine. Hepatitis B contributions included the elaboration of community-based epidemiology and description of the efficacy of immune serum globulin prophylaxis. Most recently, studies on hepatitis E defined the epidemiology, performed genomic sequencing, and developed a DNA vaccine currently being tested against the disease. Major research contributions to the understanding of and protection against viral hepatitis have been made by the military medical establishment over the past 60 years.

Esophageal ulceration due to cytomegalovirus infection in a patient with acute retroviral syndrome.

Opportunistic infections during primary infection with human immunodeficiency virus type 1 have occasionally been reported in the medical literature, and those caused by cytomegalovirus have tended to be severe and prolonged. We describe a 40-year-old man who had acute retroviral syndrome complicated by a severe cytomegalovirus-induced esophageal ulceration, which was successfully treated with total parenteral nutrition and ganciclovir in addition to highly active antiretroviral therapy.

Natural history of community-acquired methicillin-resistant Staphylococcus aureus colonization and infection in soldiers.

BACKGROUND: Community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) is an emerging pathogen for which the prevalence, risk factors, and natural history are incompletely understood. METHODS: In this prospective observational study, we evaluated 812 US Army soldiers to determine the prevalence of and risk factors for CA-MRSA colonization and the changes in colonization rate over time, as well as to determine the clinical significance of CA-MRSA colonization. Demographic data and swab samples from the nares for S. aureus cultures were obtained from participants at the start of their training and 8-10 weeks later. Over this time period, participants were observed prospectively to monitor for soft-tissue infections. S. aureus isolates were characterized by in vitro examination of antibiotic susceptibilities, mecA confirmation, pulsed-field gel electrophoresis, and Panton-Valentine leukocidin (PVL) gene testing. RESULTS: At the initial sampling, 24 of the participants (3%) were colonized with CA-MRSA, 9 of whom (38%) developed soft-tissue infections during the study period. In contrast, 229 participants (28%) were colonized with methicillin-susceptible S. aureus (MSSA), 8 (3%) of whom developed clinical infections during the same period (relative risk, 10.7; 95% confidence interval, 4.6-25.2; P<.001). At follow-up culture, the CA-MRSA colonization rate dropped to 1.6% without eradication efforts. Previous antibiotic use was a risk factor for CA-MRSA colonization at the initial sampling (P=.03). PVL genes were detected in 66% of 45 recovered CA-MRSA isolates, including all 9 clinical isolates available for analysis. Of subjects hospitalized, 5 of 6 had PVL-positive CA-MRSA infections. CONCLUSIONS: CA-MRSA colonization with PVL-positive strains was associated with a significant risk of soft-tissue infection, suggesting that CA-MRSA may be more virulent than MSSA. Previous antibiotic use may play a role in CA-MRSA colonization.

Validation of the Diesse Mini-Ves erythrocyte sedimentation rate (ESR) analyzer using the Westergren ESR method in patients with systemic inflammatory conditions.

The Diesse Mini-Ves (DMV) erythrocyte sedimentation rate (ESR) analyzer was designed to improve efficiency in determining the ESR. We compared the Westergren ESR method with the 4-sample DMV ESR analyzer for performance and clinical correlation. This prospective observational study, conducted at a 450-bed tertiary medical center, evaluated 291 paired samples from subjects with various systemic inflammatory conditions. Linear regression analysis revealed a statistically significant correlation between the 2 methods. Satisfactory precision of the DMV analyzer was obtained for high and mid-range ESR values. The 4-sample DMV ESR analyzer was precise and comparable in results to the Westergren ESR method. This DMV ESR analyzer is now used at our medical center based on quality control improvements that include a faster, safer, and more standardized ESR method. Hospital or office-based clinical laboratories should consider using the 4-sample DMV ESR analyzer in place of the Westergren method.

The effect of moving to a new hospital facility on the prevalence of methicillin-resistant Staphylococcus aureus.

BACKGROUND: The influence of hospital design on nosocomial transmission of methicillin-resistant Staphylococcus aureus (MRSA) is unknown. Our hospital's relocation to a new building with radically different ward design allowed us to study this question. Our old hospital facility had open bay wards and intensive care units, and few poorly located sinks for handwashing (bed:sink ratio 4:1). Our new hospital facility had optimized hand-washing geography and distribution of ward beds into mostly single or double rooms (bed:sink ratio 1.3:1). METHODS: We compared the prevalence of MRSA in the 2 institutions by obtaining nasal swabs from all patients on 8 selected wards and intensive care units at 2 time points both before and after the move. In addition, passive surveillance rates of MRSA for all hospitalized patients for 2 years both before and after the move were compared. Hand hygiene practices, although unrelated to the study periods, were directly observed. RESULTS: Eight of 123 patients cultured before the move were MRSA positive, compared to 5 of 138 patients cultured after the move (P=NS). MRSA prevalence determined by passive surveillance of all hospitalized patients before and after the move was also unchanged. An insignificant increase in the frequency of hand-hygiene performance following the move (20% to 23%) was observed. CONCLUSION: Radical facility design changes, which would be permissive of optimal infection control practices, were not sufficient, by themselves, to reduce the nosocomial spread of MRSA in our institution.

Frequency of vaccinia virus isolation on semipermeable versus nonocclusive dressings covering smallpox vaccination sites in hospital personnel.

BACKGROUND: The Centers for Disease Control and Prevention recommends a semipermeable occlusive dressing for hospital workers who receive smallpox vaccination. OBJECTIVE: The study was designed to determine the frequency of vaccinia virus isolation from the outer surface of semipermeable dressings and to compare the prevalence of vaccinia virus on the outer surface of semipermeable dressings with its prevalence on the outer surface of nonocclusive dressings. METHODS: A prospective, observational study was conducted on hospital employees who received smallpox vaccination at a military academic medical center. Subjects were instructed to wear a semipermeable dressing if they had direct patient contact. Employees without direct patient care had the option of wearing a semipermeable dressing or a nonocclusive dressing. Prior to a programmed dressing change, the outer surface of the bandage site was swabbed and cultured for virus. Samples were considered positive when cytopathic effects were observed, with results confirmed as vaccinia by polymerase chain reaction. RESULTS: A total of 212 cultures were obtained from 93 subjects. All cultures directly obtained from active lesions were positive (13/13). Positive cultures were obtained from 7% (10/135) of the semipermeable dressings and 23% (15/64) of the nonocclusive dressings (P <.05). Ten percent (8/79) of the semipermeable dressings with purulent exudate observed underneath the bandage were culture positive, compared with 4% (2/56) of semipermeable dressings with no purulent exudate observed underneath the bandage (P=.19). CONCLUSIONS: Compared with nonocclusive dressings, the semipermeable dressing reduced, but did not eliminate, the frequency with which vaccinia virus was cultured from the surface of the dressing. Virus was present, but only rarely, on the dressing surface in the absence of purulent exudate under the semipermeable dressings.

The effect of semipermeable dressings on smallpox vaccine site evolution.

BACKGROUND: Many hospital systems in the United States are contemplating the implementation of a smallpox vaccination program. The Centers for Disease Control and Prevention and other organizations recommend use of occlusive dressings over the vaccination site of health care workers in contact with patients. Minimal data are available on the impact of an occlusive dressing on the evolution of the vaccinia inoculation site. METHODS: We conducted a prospective observational study in which subjects were instructed to cover their vaccination site with either a semipermeable dressing over gauze or gauze alone. We recorded the duration of semipermeable dressing use and parameters pertaining to vaccination site evolution, to include time until scab separation. RESULTS: The increased use of a semipermeable dressing is associated with increased time until scab separation (n = 41, r =.48, P =.001 by regression analysis). This analysis predicts a 9-day difference in time until scab separation between patients that wore semipermeable dressings 100% of the time versus not at all. No significant correlation was observed between semipermeable dressing use and size of maximum erythema, time until maximum erythema, size of erythema on day 6 or 8, nor time until pustule formation. CONCLUSION: Semipermeable dressing use appears to prolong the time until scab separation and possibly the duration of infectivity and risk of secondary transmission. Health care organizations may wish to consider this information when instituting a smallpox vaccination program.

Coccidioidomycosis mimicking ovarian cancer.

BACKGROUND: Dissemination of coccidioidomycosis to the abdominal cavity is rare. No previous case of peritoneal coccidioidomycosis has presented as an adnexal mass. CASE: We report a case of peritoneal coccidioidomycosis mimicking ovarian carcinoma. The patient presented with a complex ovarian mass, ascites, omental caking, and an elevated CA 125. The ultimate diagnosis was not made until frozen section histopathology was performed at staging laparotomy. CONCLUSION: Peritoneal coccidioidomycosis can present with the clinical, radiographic, and serologic features of ovarian cancer. Although essential for diagnosis and staging, radiographic studies and tumor markers have limited specificity. Coccidioidomycosis now joins other benign conditions that comprise the differential diagnosis of patients who present with what seems to be advanced ovarian carcinoma. Infectious diseases consultation is recommended for the management of peritoneal coccidioidomycosis.

Prolonged stability of antimicrobial activity in peritoneal dialysis solutions.

OBJECTIVE: To evaluate the stability of the antimicrobial chemical and bioactivity of gentamicin, vancomycin, and gentamicin and vancomycin in combination, and the stability of the bioactivity of ceftazidime, admixed in standard peritoneal dialysis solutions and then maintained over a 14-day period at room temperature or under refrigeration. SETTING: Peritoneal dialysis center and microbiology laboratory at a military, teaching medical center. MEASUREMENTS: Standard peritoneal dialysate bags admixed with gentamicin, vancomycin, gentamicin and vancomycin in combination, or ceftazidime were stored at either 4 degrees C or 20 degrees C for 14 days. Sequential aliquots were withdrawn and assayed for antibiotic activity by bioassay and, except for ceftazidime, immunoassay for chemical activity. The bioassay was performed using a standardized Kirby-Bauer disc method. Significance was determined by ANOVA and, where the effect size was significant at the p < 0.05 level, the application of the paired t-test or the Wilcoxon signed rank test to the difference in activity between the first and last samples. RESULTS: Antibiotic concentration by immunoassay did not significantly deteriorate over 14 days for vancomycin or gentamicin when either room temperature or refrigerated samples were studied. By bioassay, gentamicin and ceftazidime, but not vancomycin, lost moderate but significant activity over 14 days when refrigerated bags were assayed (except for an insignificant decrement in gentamicin in the combined vancomycin and gentamicin bags). Bags stored at room temperature, in general, lost significant bioactivity over 14 days, but to levels where clinical efficacy would still be expected. The vancomycin bioassay performed on the combination bags demonstrated a remarkably enhanced bioactivity, presumably reflecting synergy with gentamicin. CONCLUSION: These data indicate that the study antibiotics admixed with peritoneal dialysis fluids retain stable chemical activity, whether refrigerated or kept at room temperature, for at least 14 days. A moderate decrement in bioactivity occurred for study antibiotics when stored either refrigerated or at room temperature over 14 days, although clinically significant levels were maintained. The clinical significance of a possible synergy between vancomycin and gentamicin is yet to be determined.

Bullis fever: a vanished infection of unknown etiology.

Camp Bullis, Texas, is an active training facility for the U.S. Army and Air Force with a storied history dating back to the late 19th century. In the early 1940s, an epidemic of a seasonal tick-borne rickettsial-like illness occurred at Camp Bullis; the last case was reported in 1947. To date, the etiology of this disease has remained elusive. In an attempt to retrospectively identify the causal pathogen, we surveyed Camp Bullis for the presumed tick vector with intent to screen molecularly for Rickettsia and Ehrlichia. However, no ticks were recovered from primary dragging attempts in the spring or from harvested deer in the fall. Moreover, pathologic and microbiologic materials obtained during the epidemic are no longer extant, making them unavailable for analysis. In this study, we review potential circumstances that impact emerging and, in this case, vanishing infections. The etiology of Bullis fever will probably remain undetermined, and this once-emerging infection may have vanished into history. However, given Camp Bullis' status as an active medical training site, awareness of and surveillance for the disease should continue.

Methicillin-resistant Staphylococcus aureus in an adult military beneficiary population lacking risk factors: susceptibility to orally available agents.

To determine the unique susceptibility of community-acquired methicillin-resistant Staphylococcus aureus (MRSA) as a function of the presence or absence of risk factors in a military beneficiary population, we reviewed all MRSA cases between 1994 and 1997 in a military medical center. Of 67 cases, 24 were community acquired, 9 of whom lacked risk factors for MRSA infection, and 43 cases were nosocomial. Among isolates from patients without risk factors, seven (77.8%) were susceptible to ciprofloxacin, eight (88.9%) to trimethoprim/sulfamethoxazole, eight (88.9%) to erythromycin, eight (88.9%) to tetracycline, and nine (100.0%) to clindamycin. These rates were markedly higher than those seen in isolates obtained from community-acquired cases with risk factors as well as from nosocomial cases (p < 0.01). Three clonal types of MRSA from patients without risk factors were identified and susceptibilities were similar for each of the three types. These results indicate that therapy with active oral agents might be reasonable for some less severe MRSA infections in our active duty military patients without risk factors, and additional studies are merited.

Experience with directly observed prophylaxis using erythromycin in military trainees exposed to pertussis.

Pertussis, once a serious respiratory disease in children, has recently been identified as a common cause of chronic cough in adults. Military personnel are known to be vulnerable to this disease. After a training barracks exposure to pertussis, routine arrangements for contact prophylaxis with erythromycin failed. This experience is reported here as well as that of our subsequent aggressive attempts using directly observed prophylaxis (DOP) with standard erythromycin regimens. No secondary cases occurred. However, many contacts (35%) could not finish a 14-day course despite DOP, mostly because of nausea (85%) or diarrhea (72%). Seventeen (18%) soldiers missed classes because of erythromycin side effects; five required emergency department visits or hospital admission for the same. Sixteen (17%) soldiers were switched to azithromycin because of side effects; all were able to complete a 14-day course without symptoms. High adherence rates with erythromycin administration using DOP are attainable but may trigger unacceptable toxicities; alternative prophylactic regimens should be considered for active duty personnel.